The present invention generally relates to steering systems, and more particularly, to a steering system for a trailer in a tractor/trailer combination.
A general illustration of a typical tractor/trailer combination 10 is shown in FIGS. 1 and 2. The trailer 12 is pivotally connected to the tractor 14 at the junction of the fifth wheel 16 and the kingpin 18, as generally known.
As seen in FIG. 2, the outside wheels of the tractor 10 generally follow the path 20 and the inside rear wheels generally follow the path 22. The inside rear wheels of the trailer 12 follow the path 24. This illustrates that, during a turn, the back end of the trailer 12 takes a path that is significantly offset from the path followed by the front of the tractor 14. As a result of such off tracking, the rear of the trailer 12 can undesirably ride over a curb even though the tractor 14 properly steers around the curb. By steering the rear wheels of the trailer 12 in a direction opposite the turning of the front wheels of the tractor 14, the amount of off tracking can be significantly reduced.
Although attempts have been made to steer the rear wheels of a trailer in a tractor/trailer combination to reduce jackknifing and off tracking, they have not been commercially successful. Examples of such systems are included in U.S. Pat. Nos. 4,244,596; 4,463,966; 4,768,802; 4,955,630; 5,282,641; 5,329,451; 6,450,523; and 6,494,476. In order to provide systems that might be considered commercially viable, the present invention provides novel structures for reading data indicative of the steering of the tractor and steering the rear wheels of the trailer in accordance with the steering data and given specifications of the particular tractor/trailer combination.